vue实现菜单切换功能

<nav>
 <ul>
 <li>
 <a :class="{active : Index == 1}" @click="changeNav(1)">学校新闻</a>
 <div v-if="Index == 1" class="line"></div>
 </li>
 <li>
 <a :class="{active : Index == 2}" @click="changeNav(2)">就业新闻</a>
 <div v-if="Index == 2" class="line"></div>
 </li>
 <li>
 <a :class="{active : Index == 3}" @click="changeNav(3)">行业新闻</a>
 <div v-if="Index == 3" class="line"></div>
 </li>
 </ul>
 </nav>

data () {
 return {
 Index:1,
}
 },

{//导航切换
changeNav(index){
 if(index == 1){

 this.Index = 1;
 }else if(index == 2){
 this.Index = 2;
 }else if(index == 3){
 this.Index = 3
 }
 },

.news-container nav li .line{
 width: 50px;
 height: 4px;
 background: #E96463;
 border: none;
 position: relative;
 top: -4px;
 right: -86px;
}
.news-container nav li .active{
 color: rgba(233,100,99,1);
}
}